Hm, I actually have a character that would fit into this setting like a glove... Sort of.

So, this character is a sort of hybrid. The idea is that she comes from a family of monster huntresses who have been interbreeding with benevolent monster girls in order to produce powerful offspring. These children tend to inherit traits from both parents that are most compatible.

In this character's case; her parents are a Dragon/Demon (Succubus) hybrid, and a vampiress. So, the traits she inherits are that of the demonic side of her "father", and her mother's vampiric traits, since those two are the most compatible. Her powers focus on using a combination of blood and soul-affecting magics to enhance/augment her physical abilities, and track & hamper enemies.

Or, think of a Reaper from Final Fantasy XIV, or a Profane Soul Blood Hunter from D&D.

Finally, as per the tradition of her family, one of her tasks is to find benevolent monster women to take as wives. For this story, I can imagine she was hired by Kyokou-sama to investigate what's going on. Especially, since her own family would have beef with The Order, for reasons that would be revealed later, if this character is approved.